DVI to VGA Problems!

[PowerPie5000]

I have a 23" LED TV/monitor combo screen manufactured by Acer (model AT2326) and i bought a cheap DVI-VGA cable off ebay because my Radeon 6870 doesn't have a VGA port. Before anyone asks about HDMI, my Xbox 360 and PS3 are occupying those ports so i'm left with a VGA port

Anyway i cannot get a stable picture and don't know if it's a fault with the screen, cable or Radeon card ?(it works fine through HDMI). The screen flickers blue when i turn on the PC (auto adjusting box pops up a few times in a row)... and Windows 7 has a blue tint and horrible picture quality (looks quite blurry/fuzzy). I connected the cable to the DVI-I port (marked VGA) on the Radeon card and stuck the other end into the TV. I also checked all the TV options of which there are hardly any.

Has anyone here had a similar problem?

[3DWizard]

So what outputs do you have on your display? Try temporarily using a different port on the display to see if you get the same weird picture. Also, sounds daft, but make sure you have installed drivers for your graphics card.

[GoNz0]

you may need an active dvi to vga adapter

[ik9000]

It could just be a faulty cable, or else pins on the connector being bent. We had one at work where we bent a pin around a bit and voila the weird colouration disappeared. (we did some research first to find out which pin was the likely culprit - didn't just launch in there)

Are you using the right kind of cable from the DVI-I output on your graphics card?

There are 3 categories of DVI cable:

DVI-A (analogue)
DVI-D (digital)
DVI-I (both analogue and digital)

Of the two digital DVI there is then a sub-category of dual link (DVI-DL, DVI-IL or DVI-IDL) which is required for HDCP ie playing of protected High Definition content. It is odd that Acer's own website say the AT2326 is not HDCP compliant, but yet it has HDMI and boast itself as full HD. Bit of a waste if not HDCP.

I think most DVI to VGA/D-SUB cables are DVI-I to VGA since this can handle an analogue output at both ends. I'm not sure if a straight DVI-A to VGA will work if the card is requiring a DVI-I output, and it definitely won't if the card is DVI-D. Nor will a DVI-D cable into a DVI-A to VGA convertor since it will lack the necessary analogue pins.

Much better info is here:

http://en.wikipedia.org/wiki/Digital_Visual_Interface

[PowerPie5000]

So what outputs do you have on your display? Try temporarily using a different port on the display to see if you get the same weird picture. Also, sounds daft, but make sure you have installed drivers for your graphics card.

Scart, Component, HDMI and VGA... My PC works perfectly using HDMI but it means i have to keep switching cables when i want to use one of the consoles. I'm using the latest Catalyst driver for my Radeon 6870.

you may need an active dvi to vga adapter

I may look into this as i've never seen an active DVI to VGA adapter (what difference does it make?).

It could just be a faulty cable, or else pins on the connector being bent. We had one at work where we bent a pin around a bit and voila the weird colouration disappeared. (we did some research first to find out which pin was the likely culprit - didn't just launch in there)

Are you using the right kind of cable from the DVI-I output on your graphics card?

There are 3 categories of DVI cable:

DVI-A (analogue)
DVI-D (digital)
DVI-I (both analogue and digital)

Of the two digital DVI there is then a sub-category of dual link (DVI-DL, DVI-IL or DVI-IDL) which is required for HDCP ie playing of protected High Definition content. It is odd that Acer's own website say the AT2326 is not HDCP compliant, but yet it has HDMI and boast itself as full HD. Bit of a waste if not HDCP.

I think most DVI to VGA/D-SUB cables are DVI-I to VGA since this can handle an analogue output at both ends. I'm not sure if a straight DVI-A to VGA will work if the card is requiring a DVI-I output, and it definitely won't if the card is DVI-D. Nor will a DVI-D cable into a DVI-A to VGA convertor since it will lack the necessary analogue pins.

Much better info is here:

http://en.wikipedia.org/wiki/Digital_Visual_Interface

I'm using the DVI-I port on my Radeon (it's marked as VGA) and the cable is a standard DVI-I to VGA type. It may just be a faulty cable.

I'm not too sure how HDCP affects my screen as i can view Blu-rays at 1080P (and at 24hz refresh) and also DVD's, DivX and other types of AVI files seem fine too (so far).

[ik9000]

blurays will play with non DL cables, but only at decreased non-HD resolution. Only when the HDCP route is detected as being intact will the system output full HD content.

Your graphics card software in the control panel usually states whether an intact HDCP route has been detected. It was this that alerted me to the fact that Dell had only included an SL DVI-D cable rather than a DL. Cheapskates.

[ik9000]

Scart, Component, HDMI and VGA... My PC works perfectly using HDMI but it means i have to keep switching cables when i want to use one of the consoles. I'm using the latest Catalyst driver for my Radeon 6870.

You can get HDMI switches eg http://www.scan.co.uk/products/kworl...-3-in-to-1-out

I may look into this as i've never seen an active DVI to VGA adapter (what difference does it make?).

I've not come across one either. Be interested to see what they do. Presumably some signal processing if it's active.

I'm using the DVI-I port on my Radeon (it's marked as VGA) and the cable is a standard DVI-I to VGA type. It may just be a faulty cable.

Easy enough to try an alternative to rule that out. Got one of those for 3 quid off Amazon just before Christmas.

[PowerPie5000]

It seems my Acer screen does support HDCP... I used the Cyberlink BD/HD advisor tool and it says "Display Connection Type: Digital (With HDCP)". I can run Blu-rays fine at 1920x1080 (full HD) and can even run them at 24hz refresh too! This is only when i use the HDMI ports.

[ik9000]

Which is my point - why do a full HD screen, put a DVI input on it but not make it dual-link? Seems a bit silly to me.

[PowerPie5000]

Which is my point - why do a full HD screen, put a DVI input on it but not make it dual-link? Seems a bit silly to me.

My Acer screen doesn't have a DVI port... It's got a standard 15-pin VGA port instead. My GPU has DVI-I, DVI-D, Displayport and HDMI connectors but no VGA, and thats why i bought a DVI-I to VGA cable so i could use the VGA input on the screen as my consoles take up the HDMI ports.

Here's another thing... I notice some cables/adapters are advertised to work from the VGA output on the GPU to a DVI input on the screen, but will they work the other way round? From the DVI output on the GPU to a VGA input on the screen? Maybe this is the problem?

[scaryjim]

Do you not have any DVI - VGA dongles lying around? You could use one of them and a normal VGA cable, and they used to come by the dozen with graphics cards a few years back (or that's how it felt, anyway ).

Or you could get a Displayport - VGA dongle, although they're more expensive.

Or you could try the cable on a different computer, or try linking a computer with native VGA out to the monitor. Basically you need to try as many possible different combinations to rule out eacxh link in the chain. My money would be on it being a dodgy cable, and I'd go for a dongle + VGA cable as the safest option...

[PowerPie5000]

My money would be on it being a dodgy cable, and I'd go for a dongle + VGA cable as the safest option...

I'm betting it's a dodgy cable too as i just tried my friends laptop using a standard VGA cable on my Acer screen and it was fine. I personally don't like those dongle adapters as one ruined a port on my old Geforce 7600GT once... The dongle sticking right out plus the weight of the VGA cable somehow broke the port (or it could have broke the pins in the adapter... I didn't check that at the time ). And surprisingly my new Radeon 6870 didn't come with any adapters (XFX seem to be getting a bit cheap these days!).

[PowerPie5000]

Ok the problem is with the screen... The laptop i tried (which worked fine for the 5 mins we tested it) is now giving the same results as my PC when i try to use the VGA port!!

I got another DVI to VGA cable (different brand) and it's no different, I also hooked up my old retro PIII Dos/Win98 rig using a native VGA cable and it was the same.... So i guess the original cable was fine and it's a fault with the screen (or the VGA port). The top part of the screen is chopped off, it's always trying to auto adjust and everything is blue (the boot-up screen is bright blue with white text instead of being black with white text!)... This only happens when using the VGA port

Anyway i'll be driving to Scan's store this week so they can sort it out while i'm there as i can't be without a screen for my PC... They can test it and should be able to do a straight swap for another one.

EDIT: I've just tested my PC using a different TV and it works via the VGA port! I forgot my 37" LG LH5000 TV had a PC VGA input (i used the cable that i first thought was faulty, but it's not)... so it's 100% definitely a problem with my Acer screen.

[ik9000]

thanks for the update. Sorry to hear it's the screen though hopefully all will be remedied easily.

[colin_e]

As mentioned above, ATI Radeon cards always used to come with at least one DVI-VGA adapter, even when the card had a native VGA port. If you don't have a one i'm sure a friend/colleague will (or eBay). This plus a standard VGA cable is simple and reliable.

Unusual to find a monitor that just plain fails to synch with a VGA signal. Worth checking that you are using timings (frame rate) your monitor specs say it should handle, but it does sound as if you have a bad monitor.

Regards: colin_e

[PowerPie5000]

As mentioned above, ATI Radeon cards always used to come with at least one DVI-VGA adapter, even when the card had a native VGA port. If you don't have a one i'm sure a friend/colleague will (or eBay). This plus a standard VGA cable is simple and reliable.

Unusual to find a monitor that just plain fails to synch with a VGA signal. Worth checking that you are using timings (frame rate) your monitor specs say it should handle, but it does sound as if you have a bad monitor.

Regards: colin_e

I can tell the VGA input is bad as soon as i power up the PC (it goes crazy trying to auto adjust and the post screen is bright blue with white text... instead of being black with white text). At first i thought it was a duff cable but now i know it's a VGA port related issue after trying different PC's and cables.